cause should produce such opposite effects

Twice in the paragraph stressing the word "cause," the Creature learns
that pleasure and pain proceed from the same force, a considerable
development in his education and mental sophistication. If this is the
groundwork of morality, however, it is important to recognize that it
shares a common bond, as the earlier quotation from Percy Bysshe Shelley's "Mutability" may remind us, with the
scientific systems that form so conspicuous a context for the novel (see
2.2.2 and note).
There are other elements emphasized in the novel that likewise exist on a
neutral ground that can result in either good or ill: curiosity, just cited by Victor, is an obvious case
in point.